java连续数字分组

public static List> groupBy(List data) {
        if (data == null) {
            return new ArrayList<>();
        }
        Collections.sort(data);
        List> result = new ArrayList<>();
        List group = null;
        for (Integer value : data) {
            if (group == null || group.get(group.size() - 1) + 1 != value) {
                group = new ArrayList<>();
                result.add(group);
            }
            group.add(value);
        }
        return result;
    }

    public static void main(String[] args) {
        List> res = groupBy(Arrays.asList(14, 1, 2, 3, 4, 7, 11, 12, 13, 17, 18));
        System.out.println(res);
    }